1. Field of the Invention
The present invention relates to an ironless rotor for an electric motor as well as the method and machine for making the same.
2. Description of the Prior Art
In order to improve the efficiency of a micromotor, a variety of methods for winding an ironless rotor using no iron core have heretofore been proposed. Most of them are directed to an ironless rotor winding wound as a rotor having a drug cup shape. Since the rotor prepared by the winding operation of this type has no iron part, there is no establishment of the hysterisis loss due to the alternate changes in the magnetic flux, and the eddy current loss at the armature side is negligible so that no iron loss need be taken as a whole into consideration. As a result, the output of the ironless motor of this type can be expressed by the following ideal equation taking no iron loss into account: EQU Iav-Ia.sup.2 R=IaEc,
wherein
R =Ra+Rb;
Ra: Winding Resistance;
Rb: Resistance of Brush;
Ia: Armature Current
V: Input Voltage
Ec: Back Electromotive Force;
IaV: Input,
Ia.sup.2 R: Copper Loss; and
IaEc: Output.
If the initial design is made such that the copper loss Ia.sup.2 R may be as low as possible for the input IaV, the output IaEc obtainable can be increased. If, moreover, the mechanical loss inclusive is sufficiently managed, it is possible to provide an ironless motor having a remarkably high efficiency. For the applications of the ironless motor, however, various problems arise in forming the lead wires if it is intended to satisfy the characteristics of the motor such as its r.p.m. or the like. For this reason, a variety of methods for winding an ironless rotor for an electric motor have been proposed. This is because the characteristics of the ironless motor are dependent largely upon the slight difference in the winding method therefor. Therefore, a number of inventions relating to the ironless rotor winding method have been conceived making stepwise improvements. However, no definitive method for winding the ironless rotor for an electric motor has never been put into practice.